Dust-collector



UNITED STATES PATENT OFFICE.

ROBERT L. BOBBITT, OF WICHITA, KANSAS, ASSIGNOR, BY DIRECT AND MESNEAS-v SIGNMEN TS, TO BOBBITT DUST COLLECTOR COMPANY, OF KANSAS CITY,MISSOURI,

A COPARTNERSHIP.

DUST-COLLECTOR.

vPatented Oct. 5, 1920.

Application led November 27, 1914. Serial No. 874,102.

T 0 all whom it may concern.'

Be it known that I, ROBERT L. Bou'r, a citizen of the United States,residing in Wichita, in the county of Sedgwick and State of Kansas, haveinvented new and useful Improvements in Dust-Collectors, of which thefollowing is a specification.

This .invention relates to improvements in dust collectors of the typeemploying an upper cylindrical portion and a lower frustoconicalportion, the dust laden air entering the cylindrical portiontangentially so as to be given a whirling motion within the device, theparticles of dust passing to the outer circumference of the collector,and the air freed from the dust escaping through an opening in the top.The dust sinks by gravity and passes out through an opening in the minorend of the device. This type of dust collector is well known and in verygeneral use. Such dust collectors are in all cases, so far as I amaware, of relatively short height compared with their width, their totalheight ranging from one-fourth to onehalf greater than the greatestdiameter, which, of course, is at the top. I have found it to benecessary to the successful operation of these devices that suiiicientspace should be provided within the tapering or frustoconical portion toprovide for the formation of what is known in the art of pneumatics as adead air space. According to my invention I construct the collector insuch a way as to form a dead space, which is practically free from dustand immediately under the outlet pipe,or opening in the top. If thisdead air space were not formed the dust would be blown out of the top ofthe collector along with the air. This latter objection is incident, ina greater or less degree, to the use of all dust collectors of thistype, and so far as I am aware no one has devised means for preventingit. This isvprobably due to the fact that as commonly used in mills, andespecially on the outside of the mill, these dust collectors are ofrelatively large diameter, and this fact has probably prevented anyonefrom discovering that an increase in the height of the device relativeto its diameter would result in a new and more effective mode ofoperation. Thus, to give an idea of the dimensions of these dustcollectors, it may be stated that the smaller sizes will approximate, inround numbers,

of the device is likewise greatly increased;

and that such radical change in the dimensions of the dust collectoryields the important result that a relatively long or deep dead or dustfree air space is formed in operation on the insideof the device; andowing to the extension of the inclined walls of the frusto-conicalportion for a great distance below this dead air space, the dust, whichis thrown by centrifugal action against the surrounding wall of thecollector, has ample opportunity to sink by gravity below said dead airspace and thus escapes being caught up by the out-going current of airwhich would otherwise blow it out of the top of the collector.

In the drawing- Figure l is a central vertical sectional view of a dustcollector constructed according to my invention; and

Fig. 2 is a plan view thereof.

Referring to the dra-wing, the dust collector is preferably constructedwith a cylindrical portion l at the top, which is provided with atangentially-arranged inlet portion 2 for the dust-laden air. The top 3is centrally apertured, and in this aperture is liXed a sleeve 4 inwhich is mounted a tube 5 which is vertically adjustable, and isdesigned to be held in adjusted positions by frictional contact with thesleeve 4. According to the volume of dust-laden air entering the inlet 2the tube 5 will be adjusted to brin its lower end nearer to or fartherfrom t esaidjnlet in order to vary the volume of air maintained in theupper portion of the dust collector; but after being once adjusted nofurther adjustment is required so long as there is no material variationin the volume of air caused to enter through the inlet 2. Depending fromthe bottom of the cylindrical portion l is a frusto-conical portion 6,which is open, as usual, at its vertex, that is, at its lower or isconstructed of suitable metal, and in sec-v tions, in the usual way, butdiffers from all dust collectors heretofore manufactured 5 prior to lnyinvention in thatl it is made of relatively great length particularly inits conical portion as compared with its greatest diameter. As the airenters the inlet 2 it develops a circumferential air current which isguided by the interior of the collector while maintaining its highvelocity, to a level below the outlet tube, and which may be properlycalled a critical level. In the interior of the collector there is alsodeveloped a central ascending column of air, the source of supply ofwhich is the lower portion of the circumferential air current. Onaccount of the relatively acute angle and great length of the conicalwall, this source of supply for the ascending air column is diffusedover a relatively extended space, from which it follows that thevelocity developed in the ascending column below the critical level isinsuicient to carry up the dust. In other words, the

high velocity circumferential-current carries the dust down in theinterior to a level from which the ascending central column is too weakto carry the dust up through the outlet tube.

In order that those skilled in the art may be able to have a basis onwhich to compare my improved dust collector with a dust collector of thetype commonly constructed, l

will state that the dust collector shown in the accompanying drawing isin true proportion, the cylindrical part 1 being about twenty-eightinches in height, and the frusto-conical portion being about seven feetin height, making the total height of the dust collector nine feet, fourinches. The diam eter of the upper or cylindrical portion, or the-greatest diameter of the device, is approximately two feet, eightinches. Thus, it will be seen that the total height of the dustcollector is about three and one-half times its greatest diameter.

While dust collectors constructed according to myinvention are now insuccessful operation I have been unable to ascertain in a scientific waythe precise relation which the length should bear to the greatestdiameter to obtain the highest efliciency in use; but I have byexperiment approximated the solution of this problem, and find that theproportion named should be not less than three to one; that is to say,the total height should be at least three times that of the greatestdiameter. l It will be understood, of

course, that the exact proportions set forth herein may be varied withincertain limits, which I am not now able to definitely state; but in allcases the total height should be considerably more than that of thegreatest diameter, and by experiments I have demonstrated that the bestresults are obtained when the .proportion above given is observed. Insuch a dust collector the upward central current passing throu h theoutlet tube 5 fails to carry up the ust. I have 70 constructed dustcollectors with a greater height relative to the diameter than thatstated without observin r any material difference in operation. I havefound, however, that when the length is materially lessened relative -tothe diameter from the proportion named th'e operation is not sosatisfactory, there being then a tendency for the dust to -blow out ofthe top.,

I claim:

1. A centrifugal dust collector consisting of an upper cyllndricalportion with a central outlet-tube projecting down into the interiorthereof, said cylindrical portion having a tangential inlet opening foradmitting the dust-laden air at a high velocity, and thereby develop acircumferential air current, said dust collector having a lower portionbelow said tube co-axialwith said cylindrical portion operating to guidesaid circumferential current while maintaining its high circumferentialvelocity, downwardly to a critical level below said tube, said lowerportion having a conical wall taperingto a vertex having a dust outletbelow said tube, and operating to develop a central ascending air columnwhose supply source is the lower portion of said circumferential aircurrent, the length of said. collector being substantially three timesthe greatest diameter thereof whereby said lower conical portion isrelatively long so that the said supply source for said ascending aircolumn is diffused over a relatively extended space, whereby the upwardvelocity of the air in said ascending column is insuflicient to carry upthe dust from below said critical level through said outlet tube, theinterior of said collector being unobstructed throughout, andv the innerface of the wall of said cylindrical 11e and conical portions beinguninterrupted.

2. A centrifugal dust collector consisting of an upper cylindricalportionV with a central upper outlet, said cylindrical portion having atangential inlet opening for admitting the dust-laden air at a highvelocity to develop a circumferential air current in said collector,said collector having a lower portion of conical form below said outlet,said 'conical portion tapering downwardly to 120 a vertex having a dustoutlet, the length of said collector being substantially three times thegreatest diameter thereof whereby the current of air passing up throughsaid upper outlet fails to carry up the dust from the interior of saidcollector.

3. A separating chamber having a tangential inlet for dust laden air andadapted to confine a whirling body of air and dust, an opening at oneend thereof for purified air,

and a relatively small centrally disposed opening at the other end fordust, said chamber having a tapering portion of the shape of a coneWhose altitude is substantially three times the diameter of its base,said dust outlet opening being adjacent to the apex of said cone.

4. A separating chamber having a cylindrical portion, a tangential inletfor dust laden air in said cylindrical portion, an outlet for puriedair, an outlet for dust, and a tapering portion of the shape of a conehaving an altitude equal to substantially three times the diameter ofits base and having a smooth uninterrupted inner surface, said dustoutlet opening being located adjacent to the apex of said cone.

In testimony whereof, I have hereunto set my hand in presence of twosubscribing wit nesses.

ROBERT L. BOBBITT. Witnesses JOHN I. NoRRIs, A. E. ELLIS.

